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Diabetic Nephropathy

Topic Overview

What is diabetic nephropathy?

Nephropathy means
kidney disease or damage. Diabetic nephropathy is damage to your kidneys caused
by
diabetes. In severe cases it can lead to kidney
failure. But not everyone with diabetes has kidney damage.

What causes diabetic nephropathy?

The kidneys have
many tiny blood vessels that filter waste from your blood. High blood sugar
from diabetes can destroy these blood vessels. Over time, the kidney isn't able
to do its job as well. Later it may stop working completely. This is called
kidney failure.

Certain things make you more likely to get diabetic nephropathy. If you
also have
high blood pressure or high cholesterol, or if you smoke, your risk is
higher. Also, Native Americans, African Americans, and Hispanics (especially
Mexican Americans) have a higher risk.

What are the symptoms?

There are no symptoms in
the early stages. So it's important to have regular urine tests to find kidney
damage early. Sometimes early kidney damage can be reversed.

As your kidneys are less
able to do their job, you may notice swelling in your body, most often in your
feet and legs.

How is diabetic nephropathy diagnosed?

The problem
is diagnosed using simple tests that check for a protein called
albumin in the urine. Urine doesn't usually contain
protein. But in the early stages of kidney damage—before you have any
symptoms—some protein may be found in your urine, because your kidneys aren't
able to filter it out the way they should.

Finding kidney damage
early can keep it from getting worse. So it's important for people with
diabetes to have regular testing, usually every year.

How is it treated?

The main treatment is medicine
to lower your blood pressure and prevent or slow the damage to your kidneys.
These medicines include:

Angiotensin-converting enzyme inhibitors,
also called ACE inhibitors.

Angiotensin II receptor blockers, also
called ARBs.

As damage to the kidneys gets worse,
your blood pressure rises. Your
cholesterol and
triglyceride levels rise too. You may need to take more than one medicine to treat these complications.

And there are other steps
you can take. For example:

Keep your blood sugar levels within your target range. This can help slow the damage to the small blood vessels in the kidneys.

Work with your doctor to keep your blood
pressure under control. Your doctor will give you a goal for your blood pressure. Your goal will be based on your health and your age. An
example of a goal is to keep your blood pressure below 140/90.

Keep your heart healthy by eating healthy foods and exercising regularly. Preventing heart disease is important, because
people with diabetes are more likely to have heart and blood
vessel diseases. And people with kidney disease are at an even higher risk for
heart disease.

Watch how much protein you eat. Eating too much is
hard on your kidneys. If diabetes has affected your kidneys, limiting how much
protein you eat may help you preserve kidney function. Talk to your doctor or
dietitian about how much protein is best for you.

Watch how much salt you eat. Eating less salt helps keep high
blood pressure from getting worse.

Don't smoke or use other
tobacco products.

How can diabetic nephropathy be prevented?

The
best way to prevent kidney damage is to keep your blood sugar in your target range and your blood pressure under control. You do this by eating healthy foods, staying at a healthy weight, exercising regularly, and
taking your medicines as directed.

At the first sign of protein in
your urine, you can take high blood pressure medicines to keep kidney damage
from getting worse.

Symptoms

There are no symptoms in the early stages of
diabetic nephropathy. If you have kidney damage, you may have small amounts of protein leaking into your urine (albuminuria).
Normally, protein is not found in urine except during periods of high fever,
strenuous exercise, pregnancy, or infection.

Not everyone with diabetes will develop diabetic nephropathy. In people with
type 1 diabetes, diabetic nephropathy is more likely to develop
5 to 10 years or more after the onset of diabetes. People with
type 2 diabetes may find out that they already have a
small amount of protein in the urine at the time diabetes is
diagnosed, because they may have had diabetes for several years.

As diabetic nephropathy progresses, your kidneys cannot do their job as well.
They cannot clear toxins or drugs from your body as well. And they cannot balance the chemicals in your blood very well. You may:

You may have symptoms if your nephropathy gets worse. These
symptoms include:

Swelling (edema), first in the feet and legs and later throughout
your body.

Poor appetite.

Weight
loss.

Weakness.

Feeling tired or worn
out.

Nausea or vomiting.

Trouble sleeping.

If the kidneys are severely damaged, blood sugar levels may drop because
the kidneys cannot remove excess
insulin or filter oral medicines that increase insulin
production.

Exams and Tests

Diabetic nephropathy is diagnosed using tests that check for a protein (albumin)
in the urine, which points to kidney damage. Your urine will be
checked for protein (urinalysis) when you are diagnosed with
diabetes.

An albumin urine test can detect
very small amounts of protein in the urine that cannot be detected by a routine
urine test, allowing early detection of nephropathy. Early detection is
important, to prevent further damage to the kidneys. The results of two tests,
done within a 3- to 6-month period, are needed to diagnose nephropathy.

When to begin checking for protein in the urine depends on the type of
diabetes you have. After testing begins, it should be done every year.footnote 1

Albumin testing

Type of diabetes

When to begin yearly
testing

Type 1 diabetes

After you have had diabetes for
5 years

Type 2 diabetes

When you are diagnosed with
diabetes

Diabetes present during
childhood

After age 10 and after the child has had diabetes for 5 years

An albuminuria dipstick test is a simple test that can
detect small amounts of protein in the urine. The strip changes color if protein is present, providing an
estimate of the amount of protein. A spot urine test for albuminuria is a
more precise lab test that can measure the exact amount of protein in a
urine sample. Either of these tests may be used to test your urine for protein.

You will also have a
creatinine test done every year. The creatinine test
is a blood test that shows how well your kidneys are working.

If
your doctor suspects that the protein in your urine may be caused by a disease
other than diabetes, other blood and urine tests may be done. You may have a
small sample of kidney tissue removed and examined (kidney biopsy).

Other tests

It is important to check your blood
pressure regularly, both at home and in your doctor's office, because blood
pressure rises as kidney damage progresses. Keeping your blood pressure at or
below your target can prevent or slow kidney damage.

Your doctor might suggest a cholesterol and triglyceride test based on your age or your risk for heart disease. Talk to your doctor about when a cholesterol test is right for you.

Treatment Overview

Diabetic nephropathy is treated with medicines that lower blood pressure and
protect the kidneys. These medicines may slow down kidney damage and are started
as soon as any amount of protein is found in the urine. The
use of these medicines before nephropathy occurs may also help prevent
nephropathy in people who have normal blood pressure.

If you have
high blood pressure, two or more medicines may be
needed to lower your blood pressure enough to protect the kidneys. Medicines
are added one at a time as needed.

It is also important to keep your blood sugar within your target range. Maintaining blood sugar levels within your target range prevents
damage to the small blood vessels in the kidneys.

Limiting the
amount of salt in your diet can help keep your high blood pressure from
getting worse. You may also want to restrict the amount of protein in your
diet. If diabetes has affected your kidneys, limiting how much protein you eat
may help you preserve kidney function. Talk to your doctor or
dietitian about how much protein is best for you.

Initial treatment

Medicines that are used to treat
diabetic nephropathy are also used to control blood
pressure. If you have a very small amount of protein in your urine, these
medicines may reverse the kidney damage. Medicines used for initial treatment
of diabetic nephropathy include:

Angiotensin-converting enzyme (ACE) inhibitors, such
as captopril, enalapril, lisinopril, and ramipril. ACE
inhibitors can lower the amount of protein being lost in the urine. Also, they
may reduce your risk of heart and blood vessel (cardiovascular) disease.

If you also have high blood pressure, two or more
medicines may be needed to lower your blood pressure enough to protect your
kidneys. Medicines are added one at a time as needed.

If you take other
medicines, avoid ones that damage or stress the kidneys, especially
nonsteroidal anti-inflammatory drugs (NSAIDs).

It is also important to keep your blood sugar within your target range to prevent damage to the small blood vessels in the kidneys.

Ongoing treatment

As
diabetic nephropathy progresses, blood pressure
usually rises, making it necessary to add more medicine to control blood
pressure.

Your doctor
may advise you to take the following medicines that lower blood pressure. You
may need to take different combinations of these medicines to best control your
blood pressure. By lowering your blood pressure, you may reduce your risk of
kidney damage. Medicines include:

Calcium channel blockers, which lower blood pressure by
making it easier for blood to flow through the vessels. Examples include
amlodipine, diltiazem, or verapamil.

Diuretics. Medicines such as
chlorthalidone, hydrochlorothiazide, or spironolactone help lower blood
pressure by removing sodium and water from the body.

Beta-blockers lower blood pressure by slowing down
your heartbeat and reducing the amount of blood pumped with each heartbeat.
Examples include atenolol, carvedilol, or metoprolol.

Continue to avoid other medicines that may damage
or stress the kidneys, especially
nonsteroidal anti-inflammatory drugs (NSAIDs). And it is still important to keep your blood sugar within your target range, eat healthy foods, get regular exercise, and not smoke.

Treatment if the condition gets worse

If damage to
the blood vessels in the kidneys continues,
kidney failure may eventually develop. When that occurs,
it is likely that you will need
dialysis treatment (renal replacement therapy)—an
artificial method of filtering the blood—or a kidney transplant to survive. To
learn more, see the topic
Chronic Kidney Disease.

What to think about

Diabetic nephropathy can
get worse during pregnancy and can affect the growth
and development of the fetus. If your nephropathy is not severe, your kidney
function may return to its prepregnancy level after the baby is born. If you
have severe nephropathy, pregnancy may lead to permanent worsening of your
kidney function.

If you have
nephropathy and are pregnant or are planning to become pregnant, talk with your
doctor about which medicines you can take. You may not be able to take some
medicines (for example, angiotensin-converting enzyme [ACE] inhibitors or angiotensin II receptor blockers [ARBs]) during pregnancy, because they
may harm your developing baby.

Avoiding X-ray tests that require IV
contrast material, such as angiograms, intravenous
pyelography (IVP), and some CT scans. IV contrast can cause further kidney
damage. If you do need to have these types of tests, make sure your doctor
knows that you have diabetic nephropathy.

Avoiding situations where
you risk losing large amounts of blood, such as unnecessary surgeries. Do not
donate blood or plasma.

Lowering your blood pressure, because high
blood pressure can make kidney damage even worse.

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